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<BLOCKQUOTE>Dear Gouzhou<BR>
<BR>
This must be the world's (or at least RASMB's) simplest suggestion on offer. Why not simply <I>measure</I> the density ? OK - you do not have a digital density meter to hand, I presume. But surely you have a decent 4-place balance around ? Just dispense 1 ml of fresh distilled water carefully into it beaker several times, note the weight each time, take the average. And then without changing pipette or tip rinse the tip with HEPES once into the sink and then repeat the process of dispense, weigh, then average. Divide average(2) by average(1) and you have the relative density of HEPES. Find the density of water at whatever temperature you have worked at, and you can convert to absolute density.<BR>
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So - the value will not be as accurate as using a DDM. But for sedimentation work, it will be fine. And it will only take you a few minutes to do.<BR>
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All best<BR>
<BR>
Arthur R owe<BR>
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Arthur J Rowe<BR>
Professor of Biomolecular Technology<BR>
NCMH Business Centre<BR>
University of Nottingham<BR>
School of Biosciences<BR>
Sutton Bonington<BR>
Leicestershire LE12 5RD UK<BR>
<BR>
Tel: +44 (0)115 951 6156<BR>
+44 (0)116 271 4502<BR>
Fax: +44 (0)115 951 6157<BR>
email: arthur.rowe@nottingham.ac.uk<BR>
arthur.rowe@connectfree.co.uk (home)<BR>
Web: www.nottingham.ac.uk/ncmh/business<BR>
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Hi, <BR>
I am using analytical ultracentrifugation to study my protein. I need<BR>
calculate the solvent density of HEPES which is not listed in BECKMAN<BR>
manual. Does anyone have the parameter for HEPES? Thanks a lot!<BR>
<BR>
Best regards,<BR>
<BR>
Guozhou Chen mailto:gchen@bio.indiana.edu<BR>
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Biology Department, Indiana University<BR>
(Home) 812-336-4099, (Lab) 812-856-0249<BR>
(Lab) http://sunflower.bio.indiana.edu/~lingchen/lab<BR>
(Personal) http://bio.indiana.edu/~gchen/main.htm<BR>
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